SARS-CoV-2 Seroprevalence at an Urban Hospital in Haiti

Background: Much to the surprise of the global community, Haiti has had far fewer COVID-19 cases and deaths than initially expected. In this study, we sought to estimate the seroprevalence of COVID-19 in a convenience cohort based in Port-au-Prince, Haiti, to elucidate potential reasons for the apparently low burden of COVID-19 in Haiti. Methods: We performed a cross-sectional analysis of SARS-CoV-2 antibody prevalence in patients aged one to 89 years old who were seen at the Haiti Adventist Hospital (HAH) laboratory between December 17, 2020, and July 3, 2021, with an order requiring a blood draw. We excluded patients outside of the age range and those who did not verbally consent to the study. We tested residual patient serum samples using the Biosys PlusTM COVID-19 IgM/IgG Rapid Test. Findings: Of 9,740 patients seen by the HAH laboratory from December 2020 to July 2021, 538 consented to have antibody testing and answer survey questions. 529 were included in the final analysis. We excluded nine participants who were aged greater than 89 (n=3), aged less than one (n=2), or had results that were not properly recorded (n=4). Three of the tested patients were repeat testers, with one who had been tested three times. These repeat results were included for a final seroprevalence analysis of 533 samples. In the final participant pool, 142 (26.6%) of 533 samples tested positive for either IgM, IgG, or both antibodies to the SARS-CoV-2 virus. Adjustment for test sensitivity resulted in an estimated seroprevalence of 28.7% (95% CI 24.9-32.9). We observed significant differences in seroprevalences among age groups, with seroprevalence increasing with age. Interpretation: The SARS-CoV-2 antibody seroprevalence in Haiti appears to be greater than the publicly reported statistics by several orders of magnitude. Furthermore, a reduced fatality rate relative to high-income countries points to uncertain factors that may confer immunologic resistance in the Haitian population.